Re: [PATCH v8 0/9] iommu/arm-smmu-v3: Adopt the crashed kernel's stream table for kdump

On Sat, Jul 18, 2026 at 01:20:52PM -0300, Jason Gunthorpe wrote:

On Fri, Jul 17, 2026 at 09:43:24PM +0000, Pranjal Shrivastava wrote:

quoted

However, looking at your approach, I think I can slightly rework my 
preservation logic and instead of bloating the KHO ABI with physical
addresses, I could re-use your exact table-walking logic during probe
to parse the live L1/L2 structures directly from registers, identify 
the valid tables, and kho/dma_restore them. There could me small 
differences though, for example instead of memremap stuff, we'd have to
use the kho/dma_restore API (which can be done by passing some op like 
the data structure writers we have?) Similarly, maybe reserving ASID/VMID 
can be potentially re-used as well..

I think this will be true for all the iommu drivers as they pretty
much all have this same kind of kdumpish adoption logic in one way or
another.

quoted

for KHO), I wanted to start a discussion to see if it makes sense to 
factor this common code out into an arm-smmu-v3-kexec.c (or similar)?

Yeah maybe so

It sounds great this helps the live update project as well!

I agree. I think the final layout can be:

# Kconfig
 config ARM_SMMU_V3_KEXEC
- 	def_bool CRASH_DUMP
+ 	def_bool CRASH_DUMP || IOMMU_LIVEUPDATE

# Makefile
 arm_smmu_v3-$(CONFIG_ARM_SMMU_V3_KEXEC) += arm-smmu-v3-kexec.o
 arm_smmu_v3-$(CONFIG_CRASH_DUMP) += arm-smmu-v3-kdump.o
+arm_smmu_v3-$(CONFIG_IOMMU_LIVEUPDATE) += arm-smmu-v3-liveupdate.o

Nicolin